The present invention relates to fluid valves of the pilot operated type having a diaphragm actuated main valve and particularly to valves of the type having the pilot valve member electrically energized. Valves of this type are commonly employed for controlling water inlet flow to household appliances such as washing machines and dish washers.
Typically, in appliance water inlet valves, an electromagnetic actuator such as a solenoid coil moves the pilot valve member to permit water at line pressure in a pilot chamber to discharge to the outlet thereby creating a pressure differential across a flexible diaphragm having the central portion thereof acting as a main valve. Forces of the pressure differential acting across the surfaces of the diaphragm then move the diaphragm to open the main valve permitting a larger flow to the outlet. Such solenoid operated pilot valves draw a very low current and therefore can be energized and deenergized by a set of electrical contacts operated by a small timing motor driven programmer.
Valves of this type are relatively low in manufacturing costs and are readily manufactured in very high volume mass production for the residential appliance industry.
In designing pilot operated diaphragm actuated valves for appliance water inlet, problems have been encountered with leakage across the main valve seating surface often caused by the trapping of foreign particles in the water supply on the main valve seat thereby preventing the valve from closing altogether.
Thus it has been desired to find a way or means of proving the reliability of closing of a pilot operated diaphragm actuated valve assembly without requiring complete redesign and retooling of the valve.